I'm very familiar with Keuka lake. I have spent many summers there. Although I fish more seriously/frequently now, when I was younger I would pass the time snorkeling in the lake.
I can say for a fact that LM are hanging out in shallow water - mostly under docks, even during the dog days of summer. SM are more elusive. Having said that I have found that SM can be located in all the traditional spots - sharp slopes and points being the most common. They are hitting all summer also - just be out there in the mornings and evenings.
I was there this past weekend - it was rainy and cold, but I had to try some new gear. Did not bother pushing the boat off the beach; I will be making better efforts in the coming weeks. Keep me posted on your progress.